Short-term reproducibility of ambulatory blood pressure monitoring in autosomal dominant polycystic kidney disease.

BACKGROUND AND

OBJECTIVES

Nondipping, defined as a less than 10% decline in Night:Day (N:D) ratio of blood pressure using 24 h ambulatory blood pressure monitoring, is associated with poor cardiovascular outcomes. However, its reproducibility has been questioned in autosomal dominant polycystic kidney disease.

MATERIALS AND

METHODS

Twenty-five of 29 recruited hypertensive or prehypertensive patients with autosomal dominant polycystic kidney disease completed ambulatory blood pressure monitoring on two occasions, 7-15 days apart, on a stable antihypertensive regimen. Daytime and night-time were defined as 6:00-21:59 h and 22:00-5:59 h, respectively. Correlation and concordance coefficients for systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate were determined based on N:D and Asleep:Awake (A:A) ratios. Consistency of dipping was assessed by using Cohen's Kappa statistics.

RESULTS

Mean (±standard deviation) for age, estimated glomerular filtration rate, differences in daytime and night-time SBP and DBP were 43.12 years (8.55 years), 63.1 ml/min (20.5 ml/min), 11.74 mmHg (8.2 mmHg), and 10.82 mmHg (6.4 mmHg), respectively. Seventeen of 25 (68%) and 18 of 25 (72%) participants maintained the same dipping category based on D:N or A:A separation. Cohen's Kappa was 0.34 for D:N ratio and 0.38 for A:A ratio. Correlation and concordance coefficients were 0.89 and 0.88 for daytime SBP, 0.91 and 0.91 for daytime DBP, 0.79 and 0.78 for night-time SBP, 0.81 and 0.80 for night-time DBP, 0.58 and 0.56 for N:D ratio of SBP, and 0.56 and 0.53 for N:D ratio of DBP. Coefficients for A:A ratio were almost identical to N:D values except for A:A ratios of SBP (0.69 and 0.67) and DBP (0.48 and 0.45).

CONCLUSION

Repeated measures of SBP and DBP, 7-15 days apart, are highly correlative and concordant in the studied population, but nondipping, even though predominant, was found to be modestly reproducible.